Microarray-based characterization of airway inflammation induced by environmental Acanthamoeba exposure versus the ovalbumin-alum model

The ovalbumin (OVA)-alum mouse model, which induces a Th2-biased immune response, is commonly used to study allergic airway inflammation. However, the artificial nature of this model limits its relevance to environmental or infection-related airway diseases. The free-living environmental protozoan Acanthamoeba is a potential trigger of airway inflammation, but its immune mechanisms remain largely unknown. To compare these 2 models of airway inflammation, this study carried out microarray-based transcriptomic analysis of lung tissue obtained from mice with OVA-alum treatment or intranasal Acanthamoeba exposure. Compared to controls, OVA-alum treatment induced broad transcriptional changes involving >2,900 probes (fold change ≥1.5); Acanthamoeba exposure led to a substantially weaker response, with <500 probes affected at the same threshold. Unlike the OVA-alum-treated group, the Acanthamoeba-exposed mice showed minimal overlap with only 5 genes significantly downregulated, suggesting a distinct immune activation profile. Downregulation of genes related to the immunoglobulin variable region (Ighv1-58 and Igkv3-10) and eosinophil function (Rnase2a) in the Acanthamoeba group suggest suppression of a typical Th2/humoral response. Heatmap and clustering analysis demonstrated clear separation between the Acanthamoeba, OVA-alum, and control groups. Taken together, these results suggest that Acanthamoeba induces a unique airway immune response that is markedly different from traditional Th2-dominant inflammation, and may be a more suitable model for studying environmentally-induced or infection-related respiratory diseases.